From d66e3664b8baf41908865ad363c6ba943e6f9c4e Mon Sep 17 00:00:00 2001
From: Amit Kapila <akapila@postgresql.org>
Date: Mon, 28 Jan 2019 07:51:02 +0530
Subject: [PATCH] In bootstrap mode, don't allow the creation of files if they
 don't already exist.

In commit's b9d01fe288 and 3908473c80, we have added some code where we
allowed the creation of files during mdopen even if they didn't exist
during the bootstrap mode.  The later commit obviates the need for same.

This was harmless code till now but with an upcoming feature where we don't
allow to create FSM for small tables, this will needlessly create FSM
files.

Author: John Naylor
Reviewed-by: Amit Kapila
Discussion: https://www.postgresql.org/message-id/CAJVSVGWvB13PzpbLEecFuGFc5V2fsO736BsdTakPiPAcdMM5tQ@mail.gmail.com
	    https://www.postgresql.org/message-id/CAA4eK1KsET6sotf+rzOTQfb83pzVEzVhbQi1nxGFYVstVWXUGw@mail.gmail.com
---
 src/backend/storage/smgr/md.c | 33 ++++++++-------------------------
 1 file changed, 8 insertions(+), 25 deletions(-)

diff --git a/src/backend/storage/smgr/md.c b/src/backend/storage/smgr/md.c
index c37dd1290b..2aba2dfe91 100644
--- a/src/backend/storage/smgr/md.c
+++ b/src/backend/storage/smgr/md.c
@@ -310,13 +310,7 @@ mdcreate(SMgrRelation reln, ForkNumber forkNum, bool isRedo)
 	{
 		int			save_errno = errno;
 
-		/*
-		 * During bootstrap, there are cases where a system relation will be
-		 * accessed (by internal backend processes) before the bootstrap
-		 * script nominally creates it.  Therefore, allow the file to exist
-		 * already, even if isRedo is not set.  (See also mdopen)
-		 */
-		if (isRedo || IsBootstrapProcessingMode())
+		if (isRedo)
 			fd = PathNameOpenFile(path, O_RDWR | PG_BINARY);
 		if (fd < 0)
 		{
@@ -572,26 +566,15 @@ mdopen(SMgrRelation reln, ForkNumber forknum, int behavior)
 
 	if (fd < 0)
 	{
-		/*
-		 * During bootstrap, there are cases where a system relation will be
-		 * accessed (by internal backend processes) before the bootstrap
-		 * script nominally creates it.  Therefore, accept mdopen() as a
-		 * substitute for mdcreate() in bootstrap mode only. (See mdcreate)
-		 */
-		if (IsBootstrapProcessingMode())
-			fd = PathNameOpenFile(path, O_RDWR | O_CREAT | O_EXCL | PG_BINARY);
-		if (fd < 0)
+		if ((behavior & EXTENSION_RETURN_NULL) &&
+			FILE_POSSIBLY_DELETED(errno))
 		{
-			if ((behavior & EXTENSION_RETURN_NULL) &&
-				FILE_POSSIBLY_DELETED(errno))
-			{
-				pfree(path);
-				return NULL;
-			}
-			ereport(ERROR,
-					(errcode_for_file_access(),
-					 errmsg("could not open file \"%s\": %m", path)));
+			pfree(path);
+			return NULL;
 		}
+		ereport(ERROR,
+				(errcode_for_file_access(),
+				 errmsg("could not open file \"%s\": %m", path)));
 	}
 
 	pfree(path);